[Some features of learning in swimming Morris test in rats selected for behavior towards human]

Some features of learning in Morris water test were studied in gray rats after a long-term selection for elimination (tame strain) and enhancement (aggressive strain) of aggressiveness towards human. The content of plasma corticosteroids was estimated at different stages of learning. It was shown that tame rats were better in performance of a special Morris task than aggressive ones. The time of search for invisible platform was increased in aggressive rats owing to the fact that they spent more time near the pool walls. Also, time of rearing at the platform was higher in tame rats compared to aggressive animals. In the retention test, rats of both strains spent significantly more time in the target quadrant than they did in other quadrants. Rats of both strains did not differ in time of search for invisible platform when it was replaced to the opposite quadrant. After the first day of learning, the corticosteroid plasma level was lower in tame rats than aggressive animals. During the following days of training, the content of the hormone increased in tame rats and did not differ from aggressive rats. It is supposed that, in tame rats, low emotionality and stress response facilitated learning in Morris water test.